What We Know About Jimmy Carter's Cancer Prognosis

— -- President Jimmy Carter revealed cancer has spread to multiple parts of his body this week, leaving many wondering about his prognosis.

A recent liver surgery showed cancer spread in the body of the 90-year-old former president. Carter has yet to disclose what type of cancer he has or what treatment he will undergo but said more information could be available as soon as next week. Representatives for Carter and Emory Healthcare, where the president is being treated, declined to offer any additional information on the prognosis.

The little public information available doesn't reveal much about what his prognosis might be, experts say.

“We know that there was a tumor in the liver and we know that there were tumors elsewhere in the body,” said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. “We don’t know where. We don’t know how many. We don’t know the size of these tumors, so all we know is cancer is present.”

“Until doctors know what the primary site of the tumor was and more importantly, the cell type at a genomic level, it is not possible to say anything about prognosis,” ABC News' Chief Health and Medical Editor Dr. Richard Besser said.

Where Did the Cancer Originate?

That’s something doctors will conduct tests to determine, but so far there aren’t any major clues to pinpoint where it started.

Carter announced he had cancer that spread after a liver surgery, suggesting the cancer may have originated in the liver, but it also could have started in another organ in the body, experts said. Several types of cancer can metastasize to the liver, including lung, colon, prostate and pancreatic cancer.

“If you think of the liver as a big filter of the blood supply, it’s easy to understand how cancers that originated in distant parts of the body can end up with metastases in the liver,” Besser said.

There is also a possibility that doctors are unable to determine where the tumor first came from using the basic tests, meaning it could be a less common form of cancer.

What Are the Treatment Options?

The treatment decisions will depend on the prognosis. There are a wide range of options to treat different types of cancer, including surgery, chemotherapy, radiation and immunotherapy. Depending on their circumstances, some patients choose not to seek treatment at all.

Carter’s age and lifestyle could be factors in how doctors plan to tackle his cancer.

“Someone who’s in their 90’s will not be able to tolerate the same side effects of treatment as someone in their 50’s or 60’s,” Lichtenfeld said.

The 90-year-old former president has maintained an active lifestyle after leaving the White House in 1981, including international travel, building homes with Habitat for Humanity, and teaching Sunday school at a Georgia Baptist church. Carter said he will adapt his schedule to fit with the treatment plan doctors develop.

Family History With Pancreatic Caner

Though no connection has been publicly made to his current cancer diagnosis, Carter’s family has a history with pancreatic cancer, one of the types of cancers that can metastasize to the liver. Carter’s father, brother and two sisters died of pancreatic cancer, and his mother also died of cancer.

In 2007, Carter revealed one reason he thinks he may have been spared from the disease.

“The only difference between me and my father and my siblings was that I never smoked a cigarette,” Carter said in an interview with the New York Times. “My daddy smoked regularly. All of them smoked.”

At the time, Carter said he had no signs of the disease and was not concerned about potentially being diagnosed with pancreatic cancer.

“I’m deeply religious, I’m a fatalist, I’m 82 years old and I’ve had a good life,” Carter said at the time.